A vehicle seat having a reclining device (a rotation prevention device) is conventionally known. In the vehicle seat, a seat back is rotatably connected to a seat cushion via the reclining device such that a tilt angle of the seat back can be adjusted. Such a reclining device is taught by Japanese Laid-Open Patent Publication Number 2006-14942. The reclining device described therein includes a disk-shaped ratchet having an internal gear wheel, a disk-shaped guide having an external gear wheel, and a retainer member that is capable of maintaining a condition in which the ratchet and the guide are axially assembled.
The retainer member is formed to a shouldered cylindrical shape. The ratchet and the guide are disposed in the cylindrical retainer member. Thus, the retainer member can be attached to the ratchet and the guide while circumferentially encircling the same. In particular, the retainer member has a support surface portion. The support surface portion is formed in one end periphery of the cylindrical retainer member by folding the periphery radially inwardly so as to have a flange shape. Therefore, when the ratchet and the guide are disposed in the cylindrical retainer member in order, an outer disk surface of the latchet can face the support surface portion.
After the ratchet and the guide are disposed in the retainer member, a reception side end periphery of the retainer member is bent radially inwardly. As a result, the ratchet and the guide can be clamped from both sides, so as to not be axially separated from each other.
According to the conventional art described above, the retainer member has the shouldered shape, so as to circumferentially encircle the ratchet and the guide that respectively have different diameters. Therefore, when the reception side end periphery of the retainer member is bent, the support surface portion formed in the opposite end periphery of the retainer member cannot have a sufficient support area that can be supported by a support die.
Thus, there is a need in the art to ensure a wide support area of a support die when an end periphery of the retainer member is bent.